A 69-year-old man visited a doctor because of systemic lymphadenopathy. Peripheral blood examination revealed leukocytosis, anemia, and decreased platelet count (WBC, 103,060/µl; lymph, 92.2%; Hb, 8.9 g/dl; and Plt, 4.1×104/µl). Bone marrow biopsy revealed that approximately 70% of nucleated cells were small, mature lymphoid cells with positive immunostaining for CD5, CD20, and CD23. He was diagnosed with chronic lymphocytic leukemia (CLL). The IgH/CCND1 translocation and ATM locus loss in 20% and 95% peripheral cells, respectively, were detected by fluorescence in situ hybridization. Immunostaining revealed that cyclin D1 was positive in approximately 30% bone marrow cells. As the positive rate of CCND1 fusion signal was low, the diagnosis of mantle cell lymphoma was excluded. In contrast, signals of ATM locus deletion were detected in most tumor cells. Therefore, we assessed that IgH/CCND1 translocations occurred during the natural clinical course of CLL with ATM locus deletion from the onset of disease. The secondary IgH/CCND1 translocation in CLL is rare, and all reported cases with such translocations received treatments with alkylating agents. This is the first report regarding secondary IgH/CCND1 translocation during the natural clinical course of CLL and may provide insights into CLL pathogenesis.
Keywords: Chronic lymphocytic leukemia; Cyclin D1; IgH/CCND1.